Zearalenone adpsortion by conidia of Aspergillus niger aggregate strains

PEREYRA CARINA; CAVAGLIERI LILIA; PENA GABRIELA; ALONSO VERONICA; CHIACCHIERA STELLA; DALCERO ANA

Congreso; ISM Conference 2009; 2009

The purpose of the present study was to evaluate the zearalenone adsorption capacity of conidia harvested from two strains of Aspergillus niger aggregate (RC84 and RC104). Dead conidia were obtained from mycelium growth on Czapek extract agar (CYA). Conidia were boiled in distilled water for 15 min. A solution of ZEA at 0; 0.5; 5; 10; 20 and 50 μg/ml in phosphate-buffered saline (PBS) at pH 2 and pH 6 was prepared. Conidia (1 x 107 conidia/ml) were incubated for 30 min at 37ºC with 1 ml PBS containing ZEA at different concentrations, separately. Conidia were pelleted by centrifugation and the supernatant containing unbound ZEA was collected. ZEA was quantified by HPLC.A theoretical model of the involved mechanism in the adsorption process was applied. This model allows estimation of parameters related to the adsorbent ability for mycotoxin adsorption: the total number of binding sites for mycotoxin (M) and the equilibrium constant (Keq) of the involved process. Both parameters are useful in selecting the most efficient adsorbent through the efficacy determination (E = M x Keq).According to this model, the strain RC84 was six times greater (6.3 x 1012) at pH 2 than pH 6. Although similar Keq was observed at both pH (2 x 104), the M value was higher at pH 2 (2.9 x 108) that at pH 6 (6.8 x 107). When the adsorption process was performed at pH 2 with RC 104 strain, the results were similar to those obtained from strain RC84. However, RC 104 at pH 6 showed a very high E (2.4 x 1014) and a Keq (5.6 x 105) that demonstrated a low reversibility of the process.Zearalenone is considered with ochratoxin as the less polar mycotoxins ad could be bound on hydrophobic surfaces. Conidia, mainly airborne types, have been reported to have a hydrophobic nature. Therefore, adsorption phenomenon of ZEA on conidia could be related to hydrophobic interactions.Conidia of A. niger aggregate RC104 could be added in feed to prevent ZEA micotoxicosis. Studies are being conducted to evaluate the adsorption process with aflatoxin B1, fumonisin B1 and ochratoxin A.